Re: [Exim] database lookups & cdbs

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Autor: Philip Hazel
Datum:  
To: robert rotman
CC: exim-users
Betreff: Re: [Exim] database lookups & cdbs
On Thu, 10 Feb 2000, robert rotman wrote:

> am in fear of managing things on my place with scripts.
> on another topic (i build an radiusbackup with a script), a small error
> accured and the backup-radius made an emty database.


It is not difficult to write lots of checks into your script. E.g. make
a new file from the database and check that it hasn't changed size
drastically from the old file (like become empty). Our script for
rebuilding DNS zones does this kind of check.

> what is the reason - when "local_domains" fails - that the mails are
> _NOT_ placed in the queue waiting there til the database is able to answer
> queries?


History. Originally Exim had no lookups that could be "off line" - they
always succeeded or failed. Local_domains is checked in a number of
places and the apparatus is not present in the code to handle
"unavailable" as a return from "is this domain in this list?" Maybe I
should investigate how much work it would be to extend all the relevant
functions so they could return more than just true/false.

I never really thought anybody would want to do anything other than use
a fast lookup on a local file for something as vital as local_domains.

> you can define backup databases as well.


... and I expect they can fail to make a good copy from the master just
as easily as your script can fail! :-) This is observed from time to
time in the DNS.

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.